Process of producing lightsensitive systems



Patented Dec. 15, 1942 mocnss or PRODUCING LIGHT- snnsrnvr: srs'rrmsOstap Stasiw, Dresden, Germany; vested in the Custodian Allen Pr rty Nomam.

dclaims.

Application June a, 1940, Serial No.

In Germany June 15, 1939 The present invention relates to a process ofproducing light-sensitive systems, and particularly is directed toimprovements in the lightsensitive substances, which are obtained by theprocess of my U. S. application, Ser. No. 306,896, filed Nov. 30, 1939.a

The light-sensitive substances described in my prior application areproduced by the introduction of alien sensitizing substances into metalhalides, for example silver sulfide into silver halide or into mixturesof them, in such a man ner, and heating the mixture to a temperature at'which said alien substance is incorporated into the silver halide byfusion, and in which the halogen liberated by dissociation during theheating, is removed.

According to the process of my above named prior application there maybe produced lightsensitive systems oi. silver chloride and silverbromide, or of mixtures of them, by sensitizing them with silversulfide. These light-sensitive systems may then be mixed with suitablecolloids, such as gelatine and the like, to prepare photographicemulsions.

I have found, that new-light-sensitive systems may be' obtained byintroducing the iodide or silver into the described light-sensitivesystems 01 silver chloride or silver bromide, or of.their mixtures.

These new light-sensitive systems excel the systems, produced accordingto my prior applica- .tion Ser. No. 306,896, in the possibility ofvarying and regulating their photographic and other properties in a highdegree. 1

80 their sensibility, their stability, the stability oi. thephotographic emulsions, prepared from them, the characteristics of thephotographic images, obtained by using them, may be influenced andregulated in a high extent.

The process of the accomplished for example in the following manner.

The light-sensitive systems 01' silver chloride or silver bromide,sensitized by silver sulfide, or mixtures 01' them are molten. Theiodide or silver is added to the molten mass and uniformly distributedin the same. Then the mass, now containing the iodide of silver, iscooled, and after cooling, is treated by heating at temperatures notexceeding 150 C. This heating results in a substantial increase in thelight sensltiveness', of the systems. V

The process of thepresent invention may be varied. It is possible, forinstance, to add the iodide of silver to the other silver halides beforepresent invention maybe the sensitizing alien substances are introducedinto them, or in any other stage of the preparation of thelight-sensitive systems. more the light-sensitive systems, containingthe silver iodide, may be obtained in a state of a fine powder byatomizing the systems when molten, for example, with the aid ofatomizing gases and/or vapours as described .in my copending applicationSerial No, 338,639, filed .June 3, 1940 or in any other convenientmanner.

The properties of the products of the invention may be furtherinfluenced by an oxidizing treat.- ment. This oxidizing treatment may becarried out in different ways and by using different oxidizingsubstances, e. g. oxygen, if desired at high temperatures and at highpressures. Furthermore the above described atomization of thelightsensitive systems maybe effected by oxidizing gases or vapours.

The light-sensitive products, produced in accordance with the process ofthe present inven, tion, may be employed without binding substances bycementing the same to suitable supports.

Furthermore they may be introduced into colloids, serving as bindingagents or carriers. Hereby emulsions are prepared, which are similar tothe photographic emulsions. These mixtures of the light-sensitiveproducts and the colloids may be poured as sheets, foils or the like, ormay be applied on suitable supports.

The introduction of the light-sensitive systems into the colloids isdone by carefully mixing them, e. g., by strongly stirring them. bytreating them by vibrations, and/or by using the distributing,dispersing and wetting agents and processes which are known in colloidalchemistry.

The pouring of the emulsions of the lightsensitive substances andcolloids in sheets or on supports may be effected by the usual methodsof making photographic plates, films, papers and.

the like. The emulsions may be applied on one side of the support orboth. They may be poured in one layer or more. Here, the usual measuresin the manufacture of photographic plates, films, papers and the likeare to be provided for, such as back-, adhering-, anti-halo-,filtering-, intermediary-, protectingand covering layers. Also, opticalphotographic sensitizers and dyestufis for coloring the layers may beadded. 'to' the emulsions or incorporated in the layers, e. g., bybathing them in the solutions of the dyestufis.

Colloids that may be used for the manufacture of the emulsions oi thelight-sensitive systems, are the diiierent species of 'gelatine, amongFurtherinto the molten mass inert gelatine, albucollodion, celluloslcesters and ethers, natural and artificial resins and polymerisates, andthe like. v

As supports for the emulsions of the lightsensitive systems and thecolloids, there may be used plates of glass, films of cellulose,collodion, cellulosic derivatives, e. g., cellulosic esters orcellulosic ethers, of resins or polymerisates, sheets of metals, paperand the like.

The pouring of the light-sensitive emulsions may be eifected accordingto the methods known in the photographic industry for the production ofphotographic films, plates, and papers.

What I claim'is: I 1. In a method of producing li t sensitive systems ofsilver halides, in which a mixture of silver halide and an aliensubstance actin as a sensitizer is heated to a temperature at which saidalien substance is incorporated into saidsilver halide by fusion .and inwhichthe halogen liberated by dissociation during the heating is removedand the resulting product is cooled, thesteps of incorporating silveriodide before cooling the same, and subjecting the cooled mass to a heattreat- ,ment at a temperature not exceeding 150 C.

2. In a method of producing light sensitive systems of silver halides,in which a mixture of silver halide and an alien substance acting as asensitizer is heated to a temperature at which said alien substance isincorporated into said silver halide by fusion and in which the ,halogenliberated by dissociation during the heating is removed and theresulting product is cooled, the steps of incorporating silver iodideinto the silver halide, and after the coolingstep reheating theresulting product, which now contains silver iodide, to a temperaturenot exceeding C.

3. In' a method of producing light sensitivesystems of silver halides,in which ,a mixture of silver bromide and silver sulfide is heated to atemperature at which said silver sulfide is incorporated intosaid-silver bromide by fusion and in which the bromide liberated bydissociation during the heating is removed and the resulting product iscooled, the steps of incorporating silver iodide into the molten massbefore cooling the same, and reheating the cooled mass after the coolingstep to a temperature not exceeding 150 C. 1

4. In a method of producing light sensitive systems of silver halides,in which a mixture of silver chloride and silver sulfide is heated to atemperature at which said silver sulfide is incorporated into saidsilver chloride by fusion,

and in which the chloride liberated by dissociation during the heatingis removed and the resulting product is cooled, the steps ofincorporating silver iodide into the molten mass before cooling thesame, and reheating the cooled mass after the cooling step to atemperature not exceeding 150 C.

' OSTAP STASIW.

